This invention relates to a technique for opening an access door of a data tape cartridge. The invention also relates to a loader mechanism incorporating the door opening device, for example, a mechanism for loading a single-reel magnetic tape cartridge into a tape drive, to enable reading data from and writing data to the tape.
Computers utilize a variety of magnetic media devices for the storage of software programs and data. Information recorded on the magnetic medium takes the form of flux transitions that represent the binary xe2x80x9c1""sxe2x80x9d and xe2x80x9c0""sxe2x80x9d that form the digital information. Tape cartridges, such as single-reel tape cartridges, are commonly used in library or other archival data storage applications. In such applications, a user or a robotic mechanism selects a tape cartridge for processing and inserts the cartridge into a tape drive coupled to a computer. In a fully automated system, a mechanism within the tape drive loads the tape from its entry point to a position in which the tape becomes accessible for read-from and write-to operations.
A variety of different size data tape cartridges are available. The drives for the different size cartridges, however, must be substantially the same size, so as to fit within a standard size slot or space available within the framework of a personal computer or the like. Larger cartridges enable storage of more data on the tape within, however, the larger the cartridge the more difficult it is to design a drive mechanism to fit within the design envelope.
A number of manufacturers have recently developed a new format based on a linear tape-open technology. This technology accommodates a range of storage requirements from single server to complex network environments, in both fast-access and high-capacity formats.
Of particular note, the high capacity tape format uses a single reel cartridge to maximize capacity, for example, for backup, restore, and archive applications. The high-capacity linear tape-open format uses a new data cartridge designed to maximize the amount of tape surface area while still enabling use of very small form factors. Present implementations of this cartridge contain 600 meters of half-inch tape and have a native storage capacity of 100 GB. The form factor for this tape cartridge is 105.4 mm wide, by 102 mm long by 21.5 mm high.
The drive mechanism for the linear tape-open high-capacity tape cartridge provides bi-directional tape motion during read/write and locate/rewind operations. The single-reel cartridge design uses a take-up reel located inside the drive. A coupler grabs a leader pin at the start of the tape and draws it out of the cartridge and around the tape head to the take-up reel in the drive. After the leader pin is secured in the take-up reel, the reel rotates and pulls the tape through the tape path. A gear built into the cartridge reel and a gear coupled to the drive reel motor form a clutch enabling the motor to drive the rotation of the tape reel within the cartridge.
A cartridge of the size used for the high-capacity for the linear tape-open format or a similarly sized competing cartridge product, by itself fills a substantial portion of the design envelope for the tape drive. In the past, tape drives for cartridges of such size have utilized manual loading mechanisms. All movement and operations to load the tape cartridge into the drive, open the tape door for access to the tape leader and engage the tape drive gear to the drive motor gear have been manual in nature. A portion of the cartridge remains outside the drive, even in the fully loaded position, to allow an operator to grip and remove the cartridge.
Data cartridge tape drives have been developed with automatic or xe2x80x9csoftxe2x80x9d loading and unloading of the cartridge. However, because of the size and complexity of the loading mechanisms, these automatic loaders have been used only in drives for smaller tape cartridges.
Also, automatic cartridge tape drives must be able to load and unload cartridges many times without jamming or other failures. A failure of an automatic loader mechanism may damage a tape cartridge, and it makes the drive unusable until repaired or replaced. Typical design parameters for drives available today call for the loader mechanism to continue to operate successfully for at least 300,000 loading/unloading cycles. For applications with frequent cartridge replacement, such as tape library systems providing access to volumes of data to many users via networks, to have a truly useful life each tape loader mechanism must operate successfully with little or no wear for many more cycles than even this design parameter.
It should, therefore, be appreciated that a need exists for an automatic loading mechanism for data tape cartridges that takes up the minimum amount of space within the design envelope of the tape drive, to allow the mechanism and the drive to handle as large a cartridge as possible. Also, a need exists for a loader mechanism of this type that is particularly durable and can operate successfully for a large number of loading/unloading cycles without any jams or other failures.
Most data tape cartridges in use today have an access door. The door normally is closed, to protect the tape media and any data stored thereon. The automatic loader for the tape drive therefore must include some mechanism that opens the access door during loading of the cartridge. A wide variety of different access-door opening mechanisms have been tried in the past. To a large extent, these mechanisms have reflected the particular structure and operation of the access door of the tape cartridge.
A number of available cartridge designs, including designs for single-reel cartridges, have used hinged doors. The opening mechanism for such a cartridge must swing the door open and into an unobtrusive position before the front of the tape cartridge gets too near the read/write head(s).
For example, U.S. Pat. No. 5,868,333 to Nayak discloses a single-reel tape cartridge design with a hinged access door, wherein the cartridge incorporates a cable and tab arrangement that serves as part of the door opening mechanism. A finger mounted in the tape drive engages the tab, to apply force through the cable to a reel around the pivot pin of the access door and pivot the door open, as the cartridge is inserted into the drive. This configuration does permit opening of the aperture door without the need for motors or electrical components.
U.S. Pat. No. 5,237,469 discloses a door opening mechanism for use in an automatic cartridge loader. This mechanism, however, utilizes a complex ratchet gear, pivot pin and lever arm arrangement. Such a mechanism requires a large number of parts, making it expensive. Because of the complexity, it would likely serve for only a relatively small number of operation cycles. Also, such a mechanism takes up considerable real estate within the design envelope of the drive.
U.S. Pat. No. 5,495,374 also discloses an automatic tape cartridge loader. This Patents suggests the use of a door opening mechanism that includes a pivotable arm with a pin that engages a slot in the tape access door. The arm pivots the tape access door at the forward end of the cartridge to open the door and expose a segment of the tape, as the cartridge is inserted into a carriage of the loader. After the door is open, the carriage assembly is automatically moved forward to carry the cartridge forward and engage the exposed segment of the tape in the cartridge with a head.
The automatic tape cartridge loader disclosed in U.S. Pat. No. 5,331,485 utilizes a spring loaded pivot member to engage and open the access door. As the cartridge support carriage moves inward, a stud follows an angled cam surface to allow the pivoting member to pivot under the force of a spring. The pivoting member includes a finger, which engages the rear extension of the access door as the pivoting member 138 pivots, to thereby push the access door open.
U.S. Pat. No. 5,543,993 discloses a door opening mechanism using a pin to engage a slot in a forward end of a pivotable door. The pin is mounted on the end of an elongate door opener frame. A door opener bearing and a pivot shaft pivotally mount a rearward end of the door opener frame and a rear end of the opener bearing to a frame of a loader mechanism adjacent a cartridge insertion slot.
The pivoting members disclosed in these three prior patents also are overly complex, making them expensive and susceptible to wear and damage. Also, these mechanisms take up too much space within the confines of the tape drive.
Many other examples of door opening mechanisms are known in the art.
Some of the prior door opening mechanisms are effective in general terms. However, few have proven effective in high volume storage applications, wherein the automatic loader incorporating the door opening mechanism must function flawlessly through a very large number of loading and unloading cycles, with little or no wear or failure and little or no wear or damage to the cartridge door. As shown by the above examples, many of the mechanisms, particularly those used in automatic loaders have been overly complex and required excessive space.
The tape cartridge for the high-capacity linear tape-open format utilizes a spring-loaded sliding door in one sidewall of the cartridge, near a front corner of the cartridge. A particular need exists for an effective mechanism to open such an access door that is adequately durable, does not adversely impact the tape cartridge or its door even in extended use and is sufficiently small to operate within the small space available in the design envelope for the drive. The door-opening mechanism itself should be quite durable and resistant to impact damage, to insure continued operation throughout a large number of cycles of the automatic loader mechanism.
The present invention meets the above-stated needs and overcomes the problems with prior cartridge loader systems.
Thus, one aspect of the invention relates to a loader for a tape cartridge. The loader includes an automatically moveable shuttle, for receiving the tape cartridge. The shuttle is arranged for movement so as to move the tape cartridge to and from a loaded position in engagement with a tape drive. The inventive loader also includes a door-opening element. This element is fixedly attached to the shuttle and occupies minimal space. This element opens a spring-loaded sliding access door on the tape cartridge in response to receipt of the cartridge in the shuttle.
Another aspect of the invention relates to an automatic tape cartridge loader, for loading an elongate, rectangular tape cartridge. The shell of the cartridge encloses a length of tape and has a pair of sides and a pair of ends. A sliding spring-loaded door in one side proximate one end of the shell provides access to a leader attached to an end of the tape. The loader includes a cartridge shuttle configured to receive the tape cartridge. The shuttle is mounted for automatic movement between a cartridge reception position and a position wherein the cartridge engages one or more operative elements of a tape drive for reading and writing of data on the length of tape. The automatic tape cartridge loader also includes a door-opening feature fixedly attached to a wall of the cartridge shuttle. The door-opening feature extends toward an interior of the cartridge shuttle. The position of the door-opening feature enables the feature to engage the sliding spring-loaded door of the cartridge shell and open the door, as the tape cartridge is inserted into the cartridge shuttle.
In the preferred embodiments, the door-opening feature is as an integral element of the wall bent inward from the wall, typically at an angle substantially perpendicular to the wall of the cartridge shuttle. The embodiments of the shuttle also include at least one cartridge-positioning feature mounted opposite the wall. The positioning feature justifies the cartridge toward the wall and the door-opening feature as the tape cartridge is inserted into the cartridge shuttle. The preferred embodiments of the cartridge-positioning feature comprise one or more extrusions projecting from a wall of the cartridge shuttle opposite the door-opening feature.
The preferred embodiment of the cartridge shuttle also includes at least one cartridge stop fixedly positioned on the cartridge shuttle to engage a forward end of the cartridge shell as the tape cartridge is inserted into the cartridge shuttle. The stop is positioned such that when the tape cartridge is inserted into the cartridge shuttle sufficiently to engage the cartridge stop, the door-opening feature has substantially fully opened the sliding spring-loaded door of the tape cartridge.
The preferred embodiments also include a number of unique elements for automatically actuating the shuttle motion. A loader embodying the inventive concepts typically includes a frame housing, and a conveyor is mounted for linear motion within the frame housing. The shuttle is mounted in the conveyor. The conveyor has opposing first and second sidewalls. In the preferred embodiments, the conveyor has a first cam profile in the first sidewall, and a second cam profile in the second sidewall, and the shuttle has attached cam follower bearings that engage the cam profiles of the conveyor.
To actuate a linear motion of the conveyor, the loader includes a rotatable actuator arm. The arm is substantially flat. The arm includes a groove at a distance from its axis of rotation. The groove edges serve as cam profiles, to drive a bearing attached to a conveyor, to move the conveyor along a linear path during loading and unloading operations. The groove edges are contoured to maintain substantially 90xc2x0 contact with a circumference of the bearing, during each linear motion of the bearing and conveyor. The actuator also preferably includes an impact buffer spring, to bias the bearing within the groove.
Rotation of the actuator arm produces the linear motion of the conveyor within the frame housing. The cam profiles on the conveyor sidewalls are angled such that interaction through the cam follower bearings produces a two-dimensional movement of the shuttle.
The preferred embodiment of the shuttle includes cantilevered springs for applying spring force toward the tape drive motor to the cartridge within the shuttle. These springs also buffer the cartridge within the shuttle. The cam profiles induce motion of the shuttle slightly past the cartridge-loaded position, to produce a gap between a surface of the cartridge and an adjacent surface of the shuttle. The cantilevered springs buffer the cartridge within the shuttle, when the shuttle moves past the cartridge-loaded position. A portion of the cantilevered spring assembly also serves as a guide, to guide the front of the cartridge into the space within the shuttle as it first enters the loader.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.